A healthcare worker who is suspected of being involved with more than 1,000 unexplained deaths in Texas, has been charged with smothering 11 murders.

Billy Chemirmir, 46, who worked as a home healthcare aide, was initially charged in 2018 with the murder of 81-year-old Lu Thi Harris.

On Tuesday, Chemirmir was indicted on six more murder charges.

According to Dallas News, Chemirmir has now been charged with killing Phyllis Payne, 91, on May 14, 2016; Phoebe Perry, 94, on June 5, 2016; and 85-year-old Norma French on October 8, 2016.

He was also charged with the murders of Doris Gleason, 92, on October 29, 2016; Rosemary Curtis, 76, on January 17, 2018; and Mary Brooks on January 31, 2018.

He has been charged with five other murders, but those identities have not been released.

Collin County confirms they have indicted Billy Chemirmir on 5 more capital murder charges. That brings the total to 12 in #Dallas and #Collin Counties. Investigators say 92-year-old Doris Gleason was one of his victims. @CBSDFWpic.twitter.com/y2b1Am9mdk